Large projects and job sites may employ hundreds or thousands of workers performing a wide variety of roles. Some construction sites may be hundreds of acres or several square miles in size. Many different employers may simultaneously employ workers on project and job sites and workers may be present on a site for varying lengths of time. Employers may interact in general contractor/subcontractor relationships. The large number of employees, their sometimes frequent movements, and the short term nature of their employment on large projects may lead to inefficiency and waste. Accurately measuring and tracking productivity in a complex services environment such as a large project can be problematic. Poor performance by a subcontractor or group of workers can disrupt the progress of an entire project. Maintaining accountability from subcontractors to general contractor to contracting organization may present significant challenges. Workers on a project site may have a variety of communications and data access needs. Worker productivity may be affected by workers' ability to communicate quickly with each other and with supervisors and to gain access to software applications and information needed to perform work and maintain job site safety.